Computer



March 14 1944f u H.B. HUNTLEY Erm, A 2,344,146

, COMPUTER Filed NOV. 4, 1943 m ATTORNEY v scribed another scale il. For cooperation with this latter scale, a scale I2 is inscribed on the intermediate member 2.

0n the equation which the calculator is designed to solve will depend the shapes of the slots i and i and the markings of the several scales. For example, for solution of the equation the scales 9 and Il are ordinary clockwise logarithmic scales on which values of a and b, resspectively, are indicated, whereas the scales II and I2 are clockwise uniform scales on which the values of c and 3:, respectively, are indicated. The range of these scales is such as to encompass the extreme values of the several variables which may be encountered.

'I'he slot l in the base member is a logarithmic spiral defined by the general polar equation in which r and o are the radial distance and the angular displacement respectively, and m and n are constants selected to give the desired scale proportions. The slot 6 in the intermediate member is an Archimedes spiral, the general polar equation of which is in which k is a constant likewise selected to obtain suitable proportions.

From the foregoing it will be apparent that if the actuating member or disc 2 is rotated to bring the value of a on scale D opposite the value of b on scale lli, the angular position of the follower member or disc I with respect to the base member I will correspond to G 10g This may be mathematically expressed as a M1 -los -5 The floating pinI moving in both spiral slot l and radial slot 1 will be moved to a radial distance r from the center such that log -n,

This distance r then equals where q represents the scale modulus reecting the eil'ect of the other scales involved. yAt the same time, the oating pin 8 must move also in the spiral slot 8 in the intermediate member 2, thereby causing the member 2 to rotate with respect to the follower member 3 through an angle assenso with' respect to the intermediate or actuating disc 2. In this connection, it should be noted that the scales II and i2 are so laid out that the zero mark on scale Il is opposed to the unit mark on scale i2 when r=m, so that the value of :cis read on scale I2 opposite the value of c on scale II.

If the equation to be solved is one such as the so-called "time to turn" equation previously re ferred to as used in aircraft radius of action problems, the arrangement of the scales and slots is somewhat diierent. In this equation t :time to turn T=total hours of usable fuel capacity a1=rate of departure, and

sn-rate of return which expression may be reduced to 10g e-lsg acoge-+1) Moreover, the scales 9 and i0 are clockwise logarlthmic scales of s1 and sa, respectively, so that the angular displacement of the follower disc 8 with respect to the base member i represents the whereas spiral slot 8 in the actuating member 2 is a spiral, the equation of which' is 10g Fil-1 1101 and the spiral slot 5 in the base member i is a logarithmic spiral having the equation T mp4-0 It is obvious from the foregoing that when the value s1 on scale 9 is brought opposite the value of sa on scale I0, the follower member or disc 3 will be displaced with respect to the intermediate member 2 through an angle representing And since the scales II and i2 are clockwise logarithmic scales of time to turn and total hours of usable fuel capacity" respectively, it is further obvious that if the scales are so located that their indices coincide when r=m+l, the time to turn may be read on the scale I I opposite the pertinent value of total hours on scale I2.

While the configuration of the arcuate or spiral slots 5 and E has been described above by reference to the mathematical expressions defining them, lprobably the easiest procedure for laying them out is the simple mechanical one. For

example, in the case of the calculator for solving the equation s-z'irl a construction disc is pivotally mounted on the member. This disc has inscribed thereon a scale corresponding to scale 9 on follower disc 3 and is cut away to provide a radial edge corresponding to the center line of the radial slot 1. Along this edge is marked a uniform scale covering the range of probable values of These values are then computed for various combinations of si and sz, and the construction disc is then rotated to bring these combinations successively opposite each' other on the respective scales. A series of marks is then made on the base member I opposite the corresponding values on the radial edge scale. and the line joining these points is the center line of the slot in the base advantage in laying out computers according to the present invention for solving problems working directly from empirical data in cases where it is not possible to set up a mathematical equation showing the relationship between the variables.

a particular angular movement of the follower disc 3 with respect to the intermediate member 2 in response to a given anguiar movement of the follower disc 3 with respect to the base member i. The combination selected should, in every case, be such that the two spiral slots meet at an angle as near 90 as possible in order to minimize side play binding of the floating pin l.

tions and changes. We claim as our invention:

1. A calculating device comprising three relatively movable of said members in response to relative movement of one of said two members with respect to the third thereof.

2. A calculating device comprising three relatively movable axially aligned members having cooperating Juxtaposed scales thereon and guideat least one of said slots being a radial slot, and means engaging inv and movable lengthwise said slots adapted to produce a prescribed relative motion between two of said members in response to relative movement of one of said two members with respect to the third thereof.

5. A calculating device comprising three relatively movable members having cooperating juxtaposed scales thereon and slots formed therein, at least two of said slots being arcuate slots arranged to intersect, and means engaging in and movable lengthwise said slots adapted to produce motion between two of said members in response to relative movement of one of said two members with respect to the third thereof.

6. A calculating device tively movable members having one of said two members thereof.

ber having a scale.. thereon and a slot formed therein, an actuating member mounted on and rotatable with respect to said base member, said actuating member having a scale thereon and a slot formed therein, a follower member mounted on said actuating member and rotatable both with respect to said actuating member and to said base member, said follower member having scales lower member relatively to the base member.

8. A calculating device comprising a base member having a scale thereon and an arcuate slot formed therein, a rst movable member having a ber relatively to said 9. A calculating device comprising three relatively movable members having cooperating juxtaposed scales thereon, each said member having formed therein a slot, two thereof being arcuate alotl and the third a radial slot, said slots beins bers in respect to relative movement of one o! arranged to provide a common point of intersecsaid members with respect to the third thereof, tion and the two arcuate slots having their arcuity and means connecting al1 three members and proreveraed, a pin ensuing in al1 three slots at said vidinz therefor a common axis of rotation. common point of intersection adapted by its 5 movement lengthwise the slots to produce a pre- HUBERT B. HUNTLEY. determined movement between two of said mem- WILLIAM VANDERSTEEL. 

